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Biomedical subjects

H L Friedman

Publications and source records attributed to H L Friedman.

At least 19 recordsLinked to original sources
PubMed1994

Reproductive health in adolescence.

The health and well-being of adolescents is closely intertwined with their physical, psychological and social development, but this is put at risk by sexual and reproductive health hazards which are increasing in much of the world. Changes in population growth and distribution, the rise of telecommunications, the increase in travel and a decline in the family, as well as a generally earlier start of menarche and later age of marriage are contributing to an increase in unprotected sexual relations before marriage. This, combined with risks from early marriage, result in too early or unwanted pregnancy and childbirth, induced abortion in hazardous circumstances and sexually transmitted diseases, including HIV infection leading to AIDS. With more than half the world's population below the age of 25, and 4 out of 5 young people living in developing countries with inadequate access to prevention and care, there is an urgent need for action. Young women are particularly vulnerable. Mortality and morbidity from early pregnancy whether ending in childbirth or abortion, is much higher for the younger adolescent. Young women, especially those who have less formal education, are more vulnerable to pressures for marriage, or sexual relations before marriage, often with older men. Young people generally lack adequate knowledge about their own development and information on how to get help. Those who could help are rarely trained for working with adolescents, and services which are generally designed for adults or children often deter young people from getting help when they most need it. Policy and legislation relating to sexual and reproductive health issues are often contradictory, and unclear or unenforced.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Induced↗
PubMed1992

Changing patterns of adolescent sexual behavior: consequences for health and development.

Sexuality is a fundamental quality of human life, important for health, happiness, individual development, and indeed for the preservation of the human race. During the dynamic period of adolescence in which the passage from childhood to maturity takes place, sexuality takes on new dimensions; feelings become more intense, relationships become more complex, and the consequences of sexual behavior are radically altered. This not only affects the behavior of young people but also of those who interact with them, their families and peers, and those who work in the health, education, youth, social welfare, and other sectors. In the contemporary world the conditions of life for many young people have also changed, and with it patterns of sexual behavior. In general, earlier puberty, later marriage, a decline in the family leading to less control and more autonomy, and intense exposure to sexual stimuli via the mass media and travel across cultural boundaries have made pre-marital adolescent sexual activity more common. This has added to traditional problems of early marriage, newer problems of early pregnancy, childbirth, and induced abortion outside of marriage, sexually transmitted diseases, and human immunodeficiency syndrome infection leading to acquired immunodeficiency syndrome. But the work of the World Health Organization (WHO), along with many others in the field, strongly suggests that given appropriate information and services, trust and equity between the sexes, young people will behave responsibly and well. In this paper some of the findings from methods developed by WHO for research, training, advocacy, and evaluation, and findings in relation to patterns and determinants of sexual and reproductive health and development will be described, and future directions suggested.

Adolescent↗
PubMed1989

The health of adolescents: beliefs and behaviour.

Adolescence is a period of transition from childhood to adulthood in which interlocking changes in the body, mind and social relationship take place. Healthy development depends on both a propitious environment and the action of adolescents themselves. A stable family, peace, material conditions for physical health, and educational, social and vocational opportunities with a chance to make use of them before marriage, are necessary environment conditions. However, within this context the adolescent must experiment with new behaviours and relationships inevitably courting some risks. Adolescent health is especially linked to behaviour. If the environment is inadequate or dangerous and the adolescent lacks self-esteem, behaviours dangerous to health are more likely to occur. These include: precocious and unprotected sexual behaviour sometimes resulting in too early or unwanted pregnancy and sexually transmitted diseases; the use of tobacco, alcohol and other drugs; injuries arising accidentally from risk taking behaviours especially when combined with alcohol or drugs; intentional injury whether self-inflicted or inflicted by others; and poor eating and habits of hygiene leading to obesity, or emaciation, acne and poor teeth and gums. Adolescent behaviour is often governed by their beliefs about what others think. Two way communication in a trusting atmosphere will reduce myths and misinformation and encourage healthy behaviour. The promotion of health, the prevention of problems, and their treatment and rehabilitation when they arise can best be accomplished with the active co-operation of young people.

Adolescent↗
PubMed1988

The thermodynamics of protein stability. Cold destabilization as a general phenomenon.

A theoretical analysis of the temperature/stability profiles of proteins shows that, where a two-state model represents the denaturation, and where the free energy of denaturation delta G(T) shows a strong temperature dependence, then the protein becomes subject to both high- and low-temperature destabilization. In the simplest case delta G(T) is parabolic, therefore the high temperature TH, where delta (G(TH) = 0, is complemented by a low temperature TL, where delta G(TL) = 0. It is generally stated that the partial molal heat capacity change delta C accompanying the heat denaturation is positive and independent of the temperature. This implies that heating the protein through TL results in a negative delta C which seems physically unsatisfactory. The constant delta C model is explored and a physically more realistic model is advanced which allows for a temperature-dependent delta C which changes sign at some temperature within the range of stability of the native protein; delta G(T) then has the form of a skewed parabola. Experimental heat capacity data for native lysozyme and for a flexible polymer lend support to this model. The molecular basis of cold inactivation of proteins is discussed in the light of the thermodynamic analysis.

Cold Temperature↗
PubMed1986

Chronic treatment with Ro 15-1788 distinguishes between its benzodiazepine antagonist, agonist and inverse agonist properties.

Ro 15-1788 (flumazepil) is an imidazodiazepine that is able to antagonise most of the behavioural actions of the benzodiazepines, as well as having some intrinsic effects. Acute administration of Ro 15-1788 (10 mg/kg) decreases social interaction between male rats and elevates exploratory head-dipping. After 5 days of pretreatment there was tolerance to the former effect, although Ro 15-1788 retained its ability to antagonise the effects on social interaction of the beta-carboline, FG 7142. Ro 15-1788 also retained its ability to elevate head-dipping: additionally, the chronically-treated rats had elevated motor activity and rearing scores. The acute effects of lorazepam in the holeboard were unchanged by chronic pretreatment with Ro-15-1788. The plasma and brain concentrations after acute administration of lorazepam were unchanged following chronic administration of Ro 15-1788. After chronic treatment the brain concentrations of Ro 15-1788 were unchanged. It is unlikely that pharmacokinetic factors could underlie the different behavioural changes following chronic treatment.

Animals↗
PubMed1978

Lifetimes of complexes of the antibiotic X-537A (lasalocid A) with physiological cations in methanol. Determination by NMR using a dissociative shift reagent.

Using a magnetic resonance method we have determined the lifetimes of the following complexes of X-537A (HX) in methanol solution at 25 degrees C, BaX+, 132 microseconds; SrX+, 34 microseconds; CaX+, 24 microseconds, and KX, 15 microseconds, each with an estimated uncertainty of 30%. For NaX and LiX the lifetimes are too short to measure by the present method. The lifetime found for BaX+ is considerably shorter than the result obtained by Patel and Shen using a different method. The present method depends upon the broadening of the resonance lines of certain protons in X- due to reactions such as X- + Ba2+ = BaX+, when the resonance of the proton in the "free" X- has been shifted from its normal frequency by Pr(III) which acts via the exchange PrX3 in equilibrium PrX2+ + X-. To determine the lifetimes of interest the equations for a three-state spin system were derived; under the relevant conditions the final equations take the form of the Swift-Connick equations for a two-state system, with the characteristics of one of the states dependent upon the PrX3 concentration. This dependence is used to extract the life-times from the data in a novel and simple way.

Anti-Bacterial Agents↗
PubMed1976

Ion binding by X-537A. Equilibrium and rate of complexation of Co(2+) in methanol.

The reaction of X-537A (XH) with Co(2+) in methanol to form the complex CoX(+) has been studied fluorometrically to determine the equilibrium constant as a function of temperature. The effect of complexation on the proton NMR spectrum of the X-537A was studied to determine the kinetics of complex formation. Comparing the data for the reaction XM(+) leads to X(-) + M(2+) in methanol at 25 degrees for several M(2+) we find that the equilibrium constants increase in the order CoX(+) less than MnX(+) and span only a factor of 5 while the rate constants increase in the order NiX(+) less than CoX(+) less than MnX(+) and span a factor of more than 100.

Anti-Bacterial Agents↗
PubMed1975

Ion binding by X-537A. Rates of complexation of Ni2+ and Mn2+ in methanol.

The rates of complexation are studied through the effects of the paramagnetic ions upon the magnetic resonances of three of the proton species in X-537A = XH. For the dissociation of the complex MX+ leads to M2+ + X- at 25 degrees the rate is (2.4 plus or minus 0.4) x 10(2) sec-1 for Ni2+ and in the range from 2 x 10(4) to 1 x 10(6) sec-1 for Mn2+. For the Ni2+ complex the activation parameters are also determined and discussed in terms of the details of the process. The difference in rate constants found here is much greater than the difference in the dissociation constants.

Anti-Bacterial Agents↗